Not only do I think an online mode could work, but I think an online Battle Royale mode could work. Every few turns the map gets smaller. Players must make their turn within 20 seconds.
I also think Valkyria Chronicles: Modern Warfare could work lol
I'd still want a traditional your-turn-my-turn structure.
Proper defense was hardly emphasized in the older VC games. All the missions focused on was pushing into enemy territory and taking their bases or killing all enemy units. At best, you had to "defend" your tank or something.
A multiplayer mode -- with all the same Command Point exploits as the normal game -- would be fantastic. It would give me a human opponent who actually takes cover and abuses the gameplay mechanics.
Even on harder difficulties, the AI can be pretty braindead. I'd say that's the franchise's biggest flaw. Harder difficulties
are harder, but not because the enemies act in novel or surprising ways.